A noise filling method is provided that includes detecting a frequency band including a part encoded to 0 from a spectrum obtained by decoding a bitstream; generating a noise component for the detected frequency band; and adjusting energy of the frequency band in which the noise component is generated and filled by using energy of the noise component and energy of the frequency band including the part encoded to 0.
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1. A noise filling apparatus comprising: at least one processor configured: to decode a bitstream of an encoded audio or speech signal to obtain spectral coefficients of a plurality of subbands; to select a subband that noise filling is applied to, from among the plurality of subbands, based on information on bit allocation of each subband, the selected subband including a spectrum coefficient quantized to zero; to obtain a noise gain for the selected subband, based on energy difference between an energy of the selected subband and an energy of decoded spectrum coefficients in the selected subband; to generate a noise component using the noise gain and random noise; to apply the generated noise component to the selected subband; and to generate a reconstructed signal of audio or speech based on the selected subband to which the generated noise component is applied.
An audio noise filling system uses a processor to improve decoded audio quality. The system decodes an encoded audio bitstream into spectral coefficients representing multiple frequency subbands. It identifies subbands suitable for noise filling, focusing on those with at least one spectral coefficient quantized to zero, indicating a lack of original audio data. For these selected subbands, it calculates a noise gain based on the energy difference between the subband's total energy and the energy of the decoded coefficients within that subband. Using this noise gain and random noise, it generates a noise component, applies it to the selected subband, and reconstructs the final audio signal.
2. The noise filling apparatus of claim 1 , wherein the processor is further configured to select the subband that noise filling is applied to, by comparing the bit allocation of the subband with a threshold.
Expanding on the noise filling system, the processor selects subbands for noise filling by comparing the bit allocation of each subband to a predefined threshold. This threshold determines the minimum bit allocation required for a subband to be considered to contain valid audio data. Subbands with bit allocations below this threshold are considered candidates for noise filling, supplementing the check for spectrum coefficients quantized to zero from the previous claim. The rest of the process (calculating noise gain, generating and applying noise, and signal reconstruction) remains the same, with this claim simply refining how subbands needing noise filling are identified.
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December 11, 2015
July 18, 2017
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